Patent GB-541779-A (GB)
Title: Improvements in or relating to apparatus for use in the starting of internal combustion engines of the free piston type
IPC: F02B71/02
Filed: 1940-04-01
Abstract: 541,779. Air compressors. SULZER FRERES SOC. ANON. April 1, 1940, No. 5817. Convention date, May 30, 1939. [Class 8 (i)] [Also in Group XXVII] In a free-piston engine having buffer cylinders 2a with pistons 5 connected to the engine pistons 3, starting is effected by compressed air admitted by a valve 9 to the buffer cylinder, which is also provided with an air-inlet valve 10 and a delivery valve 12 to enable the buffer piston to compress air at least for a time during normal running, the delivery pressure from the buffer cylinder being adjustable. In one form, Fig. 1 the pistons 3, 5 are connected to a compressor piston 4 in a cylinder 2 having inlet and delivery valves 7, 8. The internal-combustion cylinder (not shown) may be single or double acting or fitted with opposed pistons. A container 15 for starting air is connected through a cock 14 to a chamber 13 leading to the starting valve 9, and through a two-way cock 27 either to the atmosphere at 28 or to the piston 26 of a control valve 23. The chamber 13 is provided with an adjustable pressure-limiting valve 47. The sparking valve 9 is normally closed by a spring 17, and a space 21 above a piston 16 on the valve stem is connected by the control valve 23 either to the chamber 13 or to the atmosphere at 24. A pipe 35 connects the space 21 to the space beneath a piston 34 on the stem of a valve 32 admitting air from a container 29 for make-up air to the inlet valve 10 on the buffer cylinder. A pipe 43 allows the work done in the buffer cylinder to compress air into the container 15 for starting air. In operation, the cock 27 is turned to allow air pressure to act on the piston 26 moving the valve 23 on to its lower seat and connecting the space 21 to the atmosphere, and the cock 14 is opened to admit starting air to the chamber 13. The cock 27 is then turned to relieve pressure on the piston 26 so that the valve 23 opens to admit air pressure above the piston 16 to open the starting valve 9, which admits the contents of the chamber 13 to the cylinder 2a and is then closed by the spring 17. The cylinder 2a now delivers air past the valve 12 and an adjustable pressure-maintaining valve 37 to the pipe 40 and the delivery chamber of the compressor 2. As the back pressure in the chamber 41 rises, the valve 37 closes and delivery ceases. For refilling the air container 15 the spring 36 loading the valve 37 is temporarily compressed so that the delivery pressure from the cylinder 2a exceeds the pressure in the container. In a modification having opposed pistons 3, Fig. 2, the make-up pressure is admitted to the buffer cylinders 2a through piston-controlled ports 31 connected to containers 29 arranged adjacent to the cylinders and connected by a pipe 50, from which a branch 52 is connected to a pressure regulating valve 51 actuated by a piston 53 controlled by oil pressure from a pipe 57. An oil valve 56 is connected to a piston 58 subjected on one side to the air pressure in the containers 29 and pipe 50 and on the other side to the charging-air pressure from the engine cylinder 1 through a pipe 60. A spring 61 is also interposed between the piston 58 and a piston 63 adjustable by hand or by a cam 64 on the fuel-pump regulating shaft 65. The makeup pressure of the air buffers is regulated in accordance with the stroke of the pistons 3 by means of a cam 66 on the upper piston, which acts through a lever 69 to open a relief valve 69 on the pipe 50 when the piston stroke exceeds a certain limit. The lever 68 is pivoted on an eccentric on a shaft 77 adjusted by a piston 72 in accordance with the pressure in the pipe 60. To charge the containers 29 initially, a cock 79 is opened and compressed air admitted past a valve 77 until the pressure seats the valve against the action of a spring 75. Starting air is then admitted through a passage 78 and pipes 82, 83 to the chambers 13. The valve 77 may be replaced by a hand-actuated valve.